Conventional air fresheners diffusing a liquid perfume composition which is brought to an emanating surface via a wick system generally comprise a reservoir containing the fragrance composition, into which dips the wick, the latter being connected to the emanating surface. It is also quite common for the wick and the emanating surface to be part of a same component of the air freshener device. The perfume composition travels up the wick to the emanating surface, from which the perfume evaporates to freshen the surrounding atmosphere. The fragrance composition may be a true solution, a colloidal solution or a microemulsion.
Air freshener systems in which the perfume solution is aqueous-based usually contain a surface active agent to solubilize the perfume in the water. In order to achieve the desired clarity of the composition to be diffused, the products contain a surfactant system that is generally largely in excess with respect to the perfume. Typically, the ratio of surfactant to perfume is of at least 1.5, more typically between 2 and 2.5. As such surface active agents are non-volatile, they do not evaporate from the emanating surface. Moreover, the concentration of surfactant in the emanating surface gradually increases, and this in turn results in a reduced rate of perfume evaporation. There is therefore a perceivable decrease in odor intensity during the usage of the product.
Some known aqueous air fresheners contain no surfactant. U.S. Pat. Nos. 4,663,081 and 6,180,595 describe surfactant-free compositions intended for air fresheners. However both examples describe compositions that contain high levels (30 to 60% w/w) of organic solvents, which is also undesirable.
U.S. Pat. No. 4,663,081 claims that diethylene glycol monobutyl ether (DEGMBE) can, when containing dissolved perfume, incorporate a surprisingly large quantity of water compared to other glycol ethers. However, in view of the toxicity problems associated with DEGMBE, it is apparent that another solution is required.
U.S. Pat. No. 6,180,595 sets out to address the aforementioned problem. It describes compositions that contain between 30 and 60% w/w of a mixture of two glycol ether components. It also states however that the perfume composition must comprise at least 60% w/w of fragrance components having a cLogP not above 2.5. Since many perfumery ingredients useful in the field of air fresheners have a cLogP>2.5, this limitation represents a serious constraint in the creation of air freshener perfume compositions. Furthermore the ratio of organic solvent to perfume, given in the examples, is typically around 4, and thus such compositions are not very cost effective.
There is therefore still a need for a clear liquid fragrance composition containing low levels of oil-solubilizers or surfactants, so as to minimize clogging of the wick and emanating surfaces, that can effectively solubilize a wide range of fragrance ingredients regardless of their cLogP and that is non-toxic and safe to use.
It is the precisely the object of the present invention to provide such a composition and air freshener devices containing it.